Known as a conventional spectroscopic module is one comprising a block-shaped support defining a biconvex lens having a first convex surface provided with a spectroscopic unit such as a blazed diffraction grating and a second convex surface provided with a photodetector such as a photodiode (see, for example, Patent Literature 1). In such a spectroscopic module, light incident on the second convex surface is dispersed by the spectroscopic unit, and thus dispersed light is detected by the photodetector.